QGIS Workshop Su Zhang and Laura Gleasner 11/15/2018. QGIS Workshop

Transcription

1 1. Introduction to QGIS QGIS Workshop QGIS is a free and open source Geographic Information System (GIS). QGIS can help users create, edit, visualize, analyze, and publish geospatial information on various operating systems including Windows, Mac OS, Linux, BSD, etc. 2. QGIS vs. ArcGIS QGIS --- free and open source software package, more stable, less analysis tools, multi-platform ArcGIS --- commercial software package, less stable, more analysis tools, single-platform 3. Download QGIS 1) Go to 2) You will see a webpage looks like the one below; click on Download Now to go to the download page 1

2 3) Select the long term release that is compatible with your operating system to download; it is suggested to download the 64-bit version if it is compatible with your operating system 3) Click on the desired version, your browser will automatically download the QGIS installer 2

3 4. QGIS Installation 1) Double click the installer that you have downloaded 2) QGIS Setup Wizard will show up 3) Click Next to start the installation process 4) You will see the License Agreement, installation location, components to install, etc. 3

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6 5) Click Finish to complete the installation 6

7 5. Start QGIS Click on the QGIS Desktop application icon on your desktop or please go to my computer ---- all programs (all apps for Windows 10) --- QGIS Desktop Note: The first time may take a few minutes to start. For this workshop, we will only focus on vector data (points, polylines, and polygons). 1) Add Vector Layer Add Vector Layer 7

8 2) Browse to where you saved your data; make sure you choose the ESRI Shapefiles (*.shp *.SHP) file in Type to upload; load the New Mexico county boundary polygon shapefile 6. Basic Editing 1) Now you should have already successfully added the New Mexico county boundary polygon shapefile, and it should look like this 8

9 2) Right click on the layer name (tl_2010_35_county10), and then click Properties for editing; you can change the color, transparency, fill style, outline style, outline width, etc. The default symbol type is Single Symbol, but you can choose among No Symbol, Single Symbol, Categorized, Graduated, Rule-based, Inverted Polygons, and 2.5 D 9

10 7. Table Join Sometimes a single shapefile does not include all information that you want, which makes Table Join tool to be necessary and vert useful; Table Join is typically used to append the fields of one table to another through an attribute or field common to both tables 1) Click on the Add Delimited Text Layer button 0 10

11 2) The Create a Layer from Delimited Text File will pop up 3) Browse to where you saved your population data, make sure you choose the file in Microsoft Excel Comma Separated Values File format, the number of header lines to discard should be 8, and the geometry definition should be no geometry (attribute only table) 11

12 4) Right click on the layer name of the New Mexico county boundary (tl_2010_35_county10), and then click on Open Attribute Table; browse the table to find unique IDs (GEOID10) and examine it 5) Right click on the layer name of the New Mexico county boundary (tl_2010_35_county10), and then click on Properties 12

13 6) Click on Joins and then click on the green plus sign and the following dialog should appear, the john field should be COUNTY_CODE and the target field should be GEOID 10, and then click OK 13

14 7) Successfully joined process should show the following dialogue, and please click OK 8) Your standalone table should be joined with your shapefile, now right click on your shapefile layer and then click on Open Attribute Table, you can find that the two new attribute fields associated with the standalone table is appended to the back of the attribute table 14

15 9) It should be noted that this Join is temporary. In order to get a permanent joined layer, save your temporarily joined shapefile to a new shapefile; to do this, you need to right click on the joined shapefile and then click on Save As, a Save vector layer as dialogue pops up; choose the path you want to save the layer and provide a file name to the new file, and then click OK. 15

16 8. Visualize your shapefile 1) Add the newly saved shapefile (table joined) 2) Right click on the layer name, and then click on Properties 3) Click on Style 4) Click Single Symbol 5) Choose Graduated 6) Column chooses your population attribute field 7) Choose the color ramp you like 8) Choose mode of Natural Break (Jenks) for classes, and then click classify 9) Apply and then click on OK. 10) Right click on the layer name again and click on Properties, choose the labels option and then start explore the settings 16

17 11) Please at least select red color for text and choose size

18 9. Creating Maps 1) Add more shapefiles, including airport data (tra2shp) and highway (tra3sh) data 2) Explore the editing of these data 3) Click Project 4) Click on New Print Composer 5) Type in a name for your composer 18

19 6) The composition panel should appear 7) Click Layout and then click add map 8) User your mouse pointer to select the area on the white canvas of the composer for adding the map 9) Click Layout and then click Add Scalebar, Add Legend, and Add Image (for north arrow) 10) Click Composer and then click Export as Image in JPEG format 19